Boston -LRB- CNN -RRB- -- In many respects it was like a meeting of old friends : James `` Whitey '' Bulger listening carefully -- laughing heartily at one point -- to colorful recollections of former Boston bookie Richard O'Brien , who ran a successful bookmaking operation that he inherited from his father .

But this was no remember-when reunion between two elderly men .

The 84-year-old O'Brien , who lives in Florida and uses a wheel chair , testified Friday as a prosecution witness at the federal trial of Bulger , who is charged in the deaths of 19 people during the nearly two decades that prosecutors say he was the head of the Irish mob in Boston .

O'Brien described a meeting between Bulger and a man who owed him money . When the man balked at paying , Bulger replied , `` We have a business besides bookmaking . '' `` What 's that ? '' the man asked . `` Killing -LRB- expletive -RRB- like you . ''

The 83-year-old Bulger , who has shown little emotion in the first days of trial , threw his head back and let out a laugh .

At trial , Bulger edscribed as ` hands-on killer '

O'Brien said he was an `` independent '' bookmaker , or unaffiliated with a crime organization , when Bulger summoned him to a meeting to discuss joining the Bulger group .

O'Brien said had been working for the Italian mafia in Boston 's North End but Bulger told him , `` Forget the North End . If you want to be in business , you have to be with us . ''

He had no choice but to join Bulger 's Winter Hill gang , O'Brien testified , saying , `` Their reputation preceded them . ''

O'Brien then referenced Boston 's violent gang wars saying , `` A lot of people were shot . Mr. Bulger ended up on top . You can draw your own conclusions . ''

Thus began a 14-year relationship , with O'Brien testifying he paid Bulger 's group a couple of thousand dollars , cash , in `` rent '' virtually every month .

Asked why , O'Brien replied , `` I valued my life as well as those with me . ''

The monthly payment went in excess of $ 2,000 , O'Brien said , and was sometimes higher because Bulger and partner Steven `` The Rifleman '' Flemmi would charge random `` taxes '' if , for example , one of O'Brien 's workers found himself at the end of a government wiretap .

Bulger never personally took the money , which was always paid in cash . It was always handed to Bulger 's partner , Flemmi . `` Maybe he never wanted it entered into evidence , '' O'Brien offered .

O'Brien said he moved to Florida in the early '90s , turning over the day-to-day operations of his bookmaking business to one of his six daughters . Several years later , he said , he was summoned to a meeting with Flemmi amid rumblings that Bulger associates -- including a `` father-and-daughter team '' -- were starting to cooperate with the government .

He said before he left for the meeting he told his daughter , `` If I 'm not back in 12 hours go to the FBI in Miami . Do n't go home -LRB- to Boston -RRB- . Do n't go to the FBI there . ''

O'Brien is expected to continue testifying Monday .

Jurors earlier heard testimony from retired Massachusetts State Police Col. Thomas Foley , who on Thursday described the FBI 's informant program as `` poorly run . ''

`` The FBI put a higher priority protecting their informants '' than they did protecting `` public safety , '' Foley said .

Bulger 's lawyers are trying to show Bulger was allowed to act with impunity , sanctioned by corrupt FBI agents and federal prosecutors .

On cross-examination Bulger attorney Hank Brennan questioned Foley about the integrity of Bulger 's FBI informant file , which is likely to be introduced at trial , asking the retired investigator why he would accept the informant file as accurate when it was compiled by the same FBI agents Foley believed were lying to him .

Foley said he had other sources but acknowledged he had never checked the validity of the entire file .

Bulger 's lawyers also are trying to establish that Bulger was never a paid informant for the FBI and that instead Bulger was the one paying rogue agents for information .

The trial is expected to take up to three months and has the potential to reveal sensational details about the mob and FBI corruption , especially if Bulger chooses to testify .

Bulger was in hiding for 16 years before he was captured in Santa Monica , California , two years ago , living under a false name with his girlfriend in an apartment in the oceanside city .

At his July 2011 arraignment , he pleaded not guilty to the 19 murder charges and 13 other counts .

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`` Whitey '' Bulger was captured in 2011 after 16 years in hiding

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He 's charged in 19 killings during the two decades he ran Boston 's Winter Hill gang

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A former bookie testified Friday , saying he paid Bulger 's group monthly `` rent '' in cash

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`` Their reputation preceded them ... I valued my life as well as those with me ''